U.S. Pat. Nos. 3,811,467; 3,938,547; and 4,335,743, all described inventions made by Jerry Jones, teach highly successful pressure regulating apparatus for milking machine systems employed in dairies. The purpose of the apparatus described in the patents is to maintain constant the absolute pressure (vacuum) in the milking machines, regardless of the effects of numerous things tending to change the pressure.
Despite the success of the mechanisms described in the cited patents, there remained a distinct problem relative to noise generated by such mechanisms as the air flowed therethrough at considerable velocity and volume. The noise was such that dairymen tended to locate the mechanisms in positions relatively remote from the actual milking machines, so as not to disturb the cows and the persons working with them. Such remote locations of the pressure regulating mechanisms tended to reduce somewhat the degree of effectiveness of the regulation itself, in that the pressure regulators did not sense what was happening at (for example) the sets of teat cups until later. For best regulation, the pressure regulator should be located near the actual milking machines.
Another factor relative to the apparatus described in the cited patents was that air filters for the pressure regulators could not practically be removed, washed and replaced while the milking machines were operating. It is highly desirable to have filters that can be washed while the milking machines are operating. It is further desirable that such filters be large in diameter in order to increase the filter area and thus extend the period that can elapse between washings.